A step towards the application of molecular plasmonic-like excitations of PAH derivatives in organic electrochromics

Polycyclic aromatic hydrocarbons(PAHs), are regarded as molecular fragments of graphene and are facilely available through chemical synthesis. Recently, it is found collective charge density oscillations with strong induced electromagnetic field display in PAH derivatives. This phenomenon, analogue to plasmonic excitation in metal, called molecular plasmonics, arise the significant interest of physicists. Instead of discussing its rich physics, this work aims at the application of molecular plasmon-like excitations in electrochromics and optoelectronics. We found that the energy and the intensity of plasmonic-like oscillation could be largely tuned by increasing the conjugation size along both the longitude/transverse axis in PAHs. Besides, the dimeric PAH demonstrates the possibility that molecular plasmonics could be designed using PAHs as building blocks for integration into larger molecular systems. Moreover, this work straightforwardly extends the molecular plasmonic-like property from C–H composed PAHs to much more versatile planar conjugation systems with heteroatoms, achieving transferring between p-type and n-type organic semiconductors. Therefore, with the natural abundance, low cost, easily chemical synthesis of PAH derivatives, we believe this work paves the way for the application of molecular plasmonic-like properties in optoelectronics.